Paying taxes is good, lawful, even patriotic. Also good and lawful is moving a company somewhere where you'll pay less in taxes and can grow faster and hire more people (and is at worst patriotically neutral).
An exit tax is a country saying "oh no that's bad, so instead of looking at our tax structure and seeing why you're leaving and trying to address that, we're going to charge you >3 years of profit as a punishment." It's simply saying that if our taxes are too high for you we're going to charge you even more to try to stop you from leaving.
You can think it's a good thing if you don't understand economics but it's hard to frame it as anything other than Germany punishing corporations for leaving.
